According to the Centers for Disease Control (CDC), one in 33 babies is born with a congenital disability. Any agent that can cause an abnormality in an embryo or fetus is called a teratogen. These agents can lead to physical malformations, neurological problems, or even miscarriage or stillbirth. Various factors influence how teratogens can affect a pregnancy, including the genetic susceptibility of the mother and fetus, the route and dose of exposure, and the stage of pregnancy at exposure.


1. Classes of Teratogens

There are four classes of teratogens. Maternal illnesses such as diabetes can affect the development of the fetus, as can physical teratogens such as heat exposure or radiation. Chemicals such as certain medications, drugs, and toxins, can be teratogenic as well. The final class of teratogens is infections during pregnancy, which can include sexually transmitted infections, chickenpox, shingles, and other viral, bacterial or fungal infections.

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